Thermal Denitration of Ammonium Nitrate Solution in a Fluidized-Bed Reactor

Ammonium diuranate (ADU) filtrate, which contains mainly ammonium nitrate (80–100 g/L), is generated during hydrometallurgical processing of uranium. This filtrate stream poses a disposal problem because of its high nitrate content and residual radioactivity. Fluidized-bed thermal denitration is considered as a suitable chemical-free disposal option for the aqueous waste nitrate stream. Hence, investigations to explore the decomposition of ammonium nitrate in a fluidized bed have been carried out. To enable theoretical analysis and performance evaluation of the process, a mathematical model was developed. The model is based on two-phase theory of a bubbling fluidized bed. Model calculations were used to predict the axial concentration profile of ammonium nitrate in the emulsion and bubble phases and the axial temperature profiles of gas bubbles, emulsion gas, and emulsion particles. The mechanism of decomposition of ammonium nitrate in a fluidized bed was explored, and the conversion of ammonium nitrate w...